The muffler hanger is very solid and your very lucky you have the extra distance. I know of a few people who wrote me off site about the same situation, they cut the screws off as close to the compartment as they could, just so they wouldn't have to even think about having a problem later. You might want to call Winnebago and get their point of view 800-537-1885. When you find out, come back and let us know what they said.
Replying from misty and 69 degree Port Aransas TX